JP2004157384A - Electrifying member, process cartridge, and electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrifying member capable of securing the excellent uniformity of electrification by restraining the change of a surface state caused by sudden environmental change, that means, the occurrence of surface wrinkles and preventing an image defect, and to provide a process cartridge and an electrophotographic device using the electrifying member. <P>SOLUTION: The electrifying member has a conductive elastic body layer on a conductive supporting body, and a conductive covering layer as a surface layer on the conductive elastic body layer. The glass transition temperature (Tg1) of the conductive covering layer on a condition that relative humidity is 80% is 40°C<Tg1<100°C, and a difference ΔTg(=Tg2-Tg1) between the glass transition temperature (Tg2) of the conductive covering layer on a condition that the relative humidity is 55% and the Tg1 is 3°C<ΔTg<15°C. Such an electrifying member is used in the process cartridge and the electrophotographic device. <P>COPYRIGHT: (C)2004,JPO

Description

及び老化防止剤（２−メルカプトベンズイミダゾール）１質量部をオープンロールで２０分間混練し、更に加硫促進剤（ＤＭ：ｄｉｂｅｎｚｏｔｈｉａｚｙｌ ｄｉｓｕｌｆｉｄｅ）１質量部、加硫促進剤（ＴＳ：Ｔｅｔｒａｍｅｔｈｙｌｔｈｉｕｒａｍ ｍｏｎｏｓｕｌｆｉｄｅ）０．５質量部及び加硫剤としてイオウ１質量部を加えて、更に１５分間オープンロールで混練した。
【００５６】
得られた混練物をゴム押出機で、外径１５ｍｍ、内径５．５ｍｍの円筒形に押出し、２５０ｍｍの長さに裁断し、加硫缶で１６０℃の水蒸気で４０分間１次加硫し、導電性弾性体層１次加硫チューブを得た。
【００５７】
次に、直径６ｍｍ、長さ２５６ｍｍの円柱形の導電性支持体（鋼製、表面工業ニッケルメッキ）の円柱面の軸方向中央部２３１ｍｍに金属とゴムとの熱硬化性接着剤（商品名：メタロックＵ−２０）を塗布し、８０℃で３０分間乾燥した後、更に１２０℃で１時間乾燥した。この支持体を前記導電性弾性体層１次加硫チューブに挿入し、その後、電気オーブンを用い、１６０℃で２時間、２次加硫と接着剤の硬化を行い、未研磨品を得た。この未研磨品のゴム部分の両端を切断し、ゴム部分の長さを２３１ｍｍとした後、ゴム部分を回転砥石で研磨し、端部直径９．７ｍｍ、中央部１０．０ｍｍのクラウン形状で表面の十点平均粗さ（Ｒｚ）７μｍ、振れ２５μｍの導電性弾性体層を有する帯電部材を得た。
【００５８】
導電性弾性体層を有する帯電部材をＮ／Ｎ（常温常湿：２３℃、５５％ＲＨ）環境に２４時間放置し、図４に示す、円筒電極（金属ローラ）３１、固定抵抗器３２、記録計（レコーダー）３３等から構成された電流値測定装置によって、印加電圧２００Ｖでの導電性弾性体層の抵抗測定を行ったところ、１．９×１０^５Ωであった。また、硬度は７４度（アスカーＣ）であった。
【００５９】
（表面層（導電性被覆層）の形成）
導電性酸化錫粉体（商品名「ＳＮ−１００Ｐ」：石原産業（株）製）５０質量部にトリフルオロプロピルトリメトキシシランの１％イソプロピルアルコール溶液を５００質量部と平均粒子径０．８ｍｍのガラスビーズ３００質量部を加え、ペイントシェーカーで７０時間分散後、分散液を５００メッシュの網でろ過し、次にこの溶液をナウターミキサーで撹拌しながら１００℃の湯浴で暖め、アルコールを飛ばして乾燥させ、表面にシランカップリング剤を付与し、表面処理導電性酸化錫を得た。
【００６０】
更に、ラクトン変性アクリルポリオール（商品名「プラクセルＤＣ２０１６（水酸基価 ８０ＫＯＨｍｇ／ｇ）」：ダイセル化学工業（株）製）１３７質量部をＭＩＢＫ（メチルイソブチルケトン）４６３質量部に溶解し、固形分１６．０質量％の溶液とした。このアクリルポリオール溶液２００質量部に対して、前記表面処理導電性酸化錫粉体を４１．６質量部、シリコーンオイル（商品名「ＳＨ−２８ＰＡ」：東レ・ダウコーニングシリコーン（株）製）を０．０１質量部、微粒子シリカ（一次粒子径０．０２μｍ）を０．９６質量部、弾性体粒子（商品名「テクポリマー ＭＢＸ−１２」（平均粒径１２μｍ）：積水化成品工業（株）製）を２４．００質量部、直径０．８ｍｍのガラスビーズを２００質量部加えて、４５０ｍｌのマヨネーズビンに入れ、ペイントシェーカーを使用し、６時間分散した。
【００６１】
更に、この分散液３３０質量部にイソホロンジイソシアネートのブロックタイプのイソシアヌレート型３量体（ＩＰＤＩ）（商品名「ベスタナートＢ１３７０」：デグサ・ヒュルス社製）を２３．３質量部とヘキサメチレンジイソシアネートのイソシアヌレート型３量体（ＨＤＩ）（商品名「デュラネートＴＰＡ−Ｂ８０Ｅ」：旭化成工業（株）製）を１４．９質量部混合し、ボールミルで１時間撹拌し、最後に２００メッシュの網で溶液をろ過して、固形分を３９質量％とし、表面層用塗料を得た。
【００６２】
前記表面層用塗料をディッピング法により、前記導電性弾性体層を有する帯電部材の表面に塗工した。引き上げ速度４００ｍｍ／ｍｉｎで塗工し、３０分間風乾後、軸方向を反転し、再度引き上げ速度４００ｍｍ／ｍｉｎで塗工し、３０分間風乾後、オーブンを用い、１６０℃で１時間乾燥した。このとき膜厚は２５μｍであった。この表面層の電気抵抗は３．９×１０^１０Ωであった。また、帯電部材の電気抵抗を導電性弾性体層と同様にして測定したところ、５．０×１０^６Ωであった。
【００６３】
表面層の粘弾性測定は、帯電部材の表面層用塗料と同様の塗料を厚さ７５μｍのアルミシート上にバーコーターで塗布し、帯電部材の表面層形成時と同様にして乾燥することによって、約５０μｍのフィルムを形成し、得られたサンプルについてｉｔｋ ＤＶＡ−２２０動的粘弾性性測定装置（アイティー計測制御（株））を用いて測定することによって行った。Ｔｇ１の測定は、一定湿度８０％ＲＨ（窒素雰囲気下）、昇温速度４℃／ｍｉｎ、周波数１０Ｈｚ、引張モードで行った。同様にＴｇ２は、通常雰囲気（湿度５５％ＲＨ、窒素雰囲気下）、昇温速度４℃／ｍｉｎ、周波数１０Ｈｚ、引張モードで行った。実施例１のサンプルは、Ｔｇ１＝８０．０℃、Ｔｇ２＝９０．３℃、ΔＴｇ＝１０．３℃であった。
【００６４】
また、架橋密度を算出するために、上記通常雰囲気下での粘弾性特性のゴム状領域の貯蔵弾性率Ｅ’を用いて下記式を用いた。
【００６５】
ρ（Ｅ’）＝Ｅ_Ｒ’／３ＲＴ
（式中、Ｅ_Ｒ’はゴム領域の貯蔵弾性率を示し、Ｒは気体定数を示し、Ｔは絶対温度を示す。）
【００６６】
ここで、Ｅ’はＴｇ＋４０℃の値を用いた。実施例１の表面層の架橋密度ρは９．８×１０^３ｍｏｌ／ｍ^３であった。
【００６７】
（帯電部材の表面層の状態観察）
上記のようにして得られた帯電部材をＨ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置し、その表面状態について、１日ごとに１週間、目視により確認した。表面にシワがないものを○、端部にシワが少し発生したものを△、帯電部材全体にシワの発生したものを×とした。
【００６８】
（画像の評価）
上記のようにして得られた帯電部材を用いて、以下に示すようにして画像評価を行った。
【００６９】
本試験で使用した電子写真式レーザープリンターは、帯電部材と感光体を一体に有するプロセスカートリッジを具備する反転現像方式のＡ４縦出力用のマシンで、記録メディアの出力スピードは、９４ｍｍ／ｓｅｃで、画像解像度は６００ｄｐｉである。
【００７０】
感光体はアルミシリンダーに膜厚１８μｍのＯＰＣ層をコートした感光ドラムであり、最外層は変性ポリカーボネートをバインダー樹脂とする電荷輸送層である。トナーは、ワックスを中心に電荷制御剤と色素等を含有するスチレンとブチルアクリレートのランダムコポリマーを重合させ、更に表面にポリエステル薄層を重合させシリカ微粒子を外添した。このトナーのガラス転移温度は６３℃、体積平均粒子径６μｍの重合トナーである。
【００７１】
画像の評価は全て、低温低湿環境（Ｌ／Ｌ：１５℃、１０％ＲＨ）で行い、Ａ４ハーフトーン（感光体の回転方向と垂直方向に幅１ドット、間隔２ドットの横線を描く画像）画像を出力し、帯電部材の表面シワに起因する帯電ムラが発生してないかどうかを目視により観察した。帯電ムラが発生していないものを◎、少し発生したものを○、中程度に発生したものを△、非常にムラが大きかったものを×とした。
【００７２】
実施例１の帯電部材は、Ｈ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置しても表面にシワが発生することも全く無く、その後の画出し評価でも画像ムラの発生も無く、全く問題なかった。
【００７３】
［実施例２］
実施例１と同様にして、導電性支持体上に導電性弾性体層を形成した。
【００７４】
次に、ラクトン変性アクリルポリオール（商品名「プラクセルＤＣ２２０９（水酸基価 １２ＫＯＨｍｇ／ｇ）」：ダイセル化学工業（株）製）１４４質量部をＭＩＢＫ（メチルイソブチルケトン）４５６質量部に溶解し、固形分１６．０質量％の溶液とした。このアクリルポリオール溶液２００質量部に対して、前記表面処理導電性酸化錫粉体を３１．２質量部、シリコーンオイル（商品名「ＳＨ−２８ＰＡ」：東レ・ダウコーニングシリコーン（株）製）を０．０１質量部、微粒子シリカ（一次粒子径０．０２μｍ）を０．７２質量部、弾性体粒子（商品名「テクポリマー ＭＢＸ−１２」（平均粒径１２μｍ）：積水化成品工業（株）製）を１８．００質量部、直径０．８ｍｍのガラスビーズを２００質量部加えて、４５０ｍｌのマヨネーズビンに入れ、ペイントシェーカーを使用し、６時間分散した。
【００７５】
更に、この分散液３３０質量部にイソホロンジイソシアネートのブロックタイプのイソシアヌレート型３量体（ＩＰＤＩ）（商品名「ベスタナートＢ１３７０」：デグサ・ヒュルス社製）を４．８質量部とヘキサメチレンジイソシアネートのイソシアヌレート型３量体（ＨＤＩ）（商品名「デュラネートＴＰＡ−Ｂ８０Ｅ」：旭化成工業（株）製）を３．１質量部混合し、ボールミルで１時間撹拌し、最後に２００メッシュの網で溶液をろ過して、固形分を３０質量％とし、表面層用塗料を得た。
【００７６】
上記塗料を用い、実施例１と同様の条件でディッピング塗布し、乾燥することによって、実施例２の帯電部材を得た。このときの表面層の膜厚は３０μｍであり、電気抵抗は２．７×１０^１０Ωであった。また、この帯電部材の電気抵抗は３．５×１０^６Ωであった。
【００７７】
更に、粘弾性測定の結果、Ｔｇ１＝５０．９℃、Ｔｇ２＝５８．３℃、ΔＴｇ＝７．４℃で、架橋密度ρ＝９．３×１０^３ｍｏｌ／ｍ^３であった。
【００７８】
実施例２の帯電部材は、Ｈ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置しても表面にシワが発生することも全く無く、その後の画出し評価でも画像ムラの発生も無く、全く問題なかった。
【００７９】
［実施例３］
実施例１と同様にして、導電性支持体上に導電性弾性体層を形成した。
【００８０】
次に、ラクトン変性アクリルポリオール（商品名「プラクセルＤＣ２００９（水酸基価 ９０ＫＯＨｍｇ／ｇ）」：ダイセル化学工業（株）製）１３７質量部をＭＩＢＫ（メチルイソブチルケトン）４６３質量部に溶解し、固形分１６．０質量％の溶液とした。このアクリルポリオール溶液２００質量部に対して、前記表面処理導電性酸化錫粉体を３１．２質量部、シリコーンオイル（商品名「ＳＨ−２８ＰＡ」：東レ・ダウコーニングシリコーン（株）製）を０．０１質量部、微粒子シリカ（一次粒子径０．０２μｍ）を０．９６質量部、弾性体粒子（商品名「テクポリマー ＭＢＸ−１２」（平均粒径１２μｍ）：積水化成品工業（株）製）を２４．００質量部、直径０．８ｍｍのガラスビーズを２００質量部加えて、４５０ｍｌのマヨネーズビンに入れ、ペイントシェーカーを使用し、６時間分散した。
【００８１】
更に、この分散液３３０質量部にＰＰＧ（ポリプロピレンエーテルグリコール）主鎖で両末端がポリメリックＭＤＩ（ジフェニルメタンジイソシアネート）でＭＥＫ（メチルエチルケトン）オキシムでブロックされたブロックイソシアネート（商品名「コロネート２５２０」：日本ポリウレタン製）を４４．９質量部とヘキサメチレンジイソシアネートのイソシアヌレート型３量体（ＨＤＩ）（商品名「デュラネートＴＰＡ−Ｂ８０Ｅ」：旭化成工業（株）製）を１５．１質量部混合し、ボールミルで１時間撹拌し、最後に２００メッシュの網で溶液をろ過して、固形分を４１．５質量％とし、表面層用塗料を得た。
【００８２】
上記塗料を用い、実施例１と同様の条件でディッピング塗布し、乾燥することによって、実施例３の帯電部材を得た。このときの表面層の膜厚は２５μｍであり、電気抵抗は３．２×１０^１０Ωであった。また、この帯電部材の電気抵抗は４．６×１０^６Ωであった。
【００８３】
更に、粘弾性測定の結果、Ｔｇ１＝６７．９℃、Ｔｇ２＝７６．３℃、ΔＴｇ＝８．４℃で、架橋密度ρ＝５．６×１０^３ｍｏｌ／ｍ^３であった。
【００８４】
実施例３の帯電部材は、Ｈ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置しても表面にシワが発生することも全く無く、その後の画出し評価でも画像ムラの発生も無く、全く問題なかった。
【００８５】
［実施例４］
実施例１と同様にして、導電性支持体上に導電性弾性体層を形成した。
【００８６】
次に、ラクトン変性アクリルポリオール（商品名「プラクセルＤＣ２００９（水酸基価 ９０ＫＯＨｍｇ／ｇ）」：ダイセル化学工業（株）製）１３７質量部をＭＩＢＫ（メチルイソブチルケトン）４６３質量部に溶解し、固形分１６．０質量％の溶液とした。このアクリルポリオール溶液２００質量部に対して、前記表面処理導電性酸化錫粉体を４１．６質量部、シリコーンオイル（商品名「ＳＨ−２８ＰＡ」：東レ・ダウコーニングシリコーン（株）製）を０．０１質量部、微粒子シリカ（一次粒子径０．０２μｍ）を０．９６質量部、弾性体粒子（商品名「テクポリマー ＭＢＸ−１２」（平均粒径１２μｍ）：積水化成品工業（株）製）を２４．００質量部、直径０．８ｍｍのガラスビーズを２００質量部加えて、４５０ｍｌのマヨネーズビンに入れ、ペイントシェーカーを使用し、６時間分散した。
【００８７】
更に、この分散液３３０質量部に無変性のポリメリックＭＤＩをＭＥＫオキシムでブロックしたブロックイソシアネート（商品名「コロネート２５１６」：日本ポリウレタン製）を１５．３質量部とヘキサメチレンジイソシアネートのイソシアヌレート型３量体（ＨＤＩ）（商品名「デュラネートＴＰＡ−Ｂ８０Ｅ」：旭化成工業（株）製）を１６．５質量部混合し、ボールミルで１時間撹拌し、最後に２００メッシュの網で溶液をろ過して、固形分を４０．０質量％とし、表面層用塗料を得た。
【００８８】
上記塗料を用い、実施例１と同様の条件でディッピング塗布し、乾燥することによって、実施例４の帯電部材を得た。このときの表面層の膜厚は１８μｍであり、電気抵抗は４．０×１０^１０Ωであった。また、この帯電部材の電気抵抗は５．１×１０^６Ωであった。
【００８９】
更に、粘弾性測定の結果、Ｔｇ１＝６９．８℃、Ｔｇ２＝８２．２℃、ΔＴｇ＝１２．４℃で、架橋密度ρ＝８．８×１０^３ｍｏｌ／ｍ^３であった。
【００９０】
実施例４の帯電部材は、Ｈ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置すると７日後に若干端部に軽微なシワが確認されたが、その後の画出し評価でもその部分の画像ムラが少し発生した。
【００９１】
［実施例５］
実施例１と同様にして、導電性支持体上に導電性弾性体層を形成した。
【００９２】
また、ラクトン変性アクリルポリオール（商品名「プラクセルＤＣ２０１６（水酸基価 ８０ＫＯＨｍｇ／ｇ）」：ダイセル化学工業（株）製）１６３質量部をＭＩＢＫ（メチルイソブチルケトン）４３７質量部に溶解し、固形分１９．０質量％の溶液とした。このアクリルポリオール溶液２００質量部に対して、前記表面処理導電性酸化錫粉体を４９．４質量部、シリコーンオイル（商品名「ＳＨ−２８ＰＡ」：東レ・ダウコーニングシリコーン（株）製）を０．０１質量部、微粒子シリカ（一次粒子径０．０２μｍ）を１．１４質量部、弾性体粒子（商品名「テクポリマー ＭＢＸ−１２」（平均粒径１２μｍ）：積水化成品工業（株）製）を２８．５０質量部、直径０．８ｍｍのガラスビーズを２００質量部加えて、４５０ｍｌのマヨネーズビンに入れ、ペイントシェーカーを使用し、６時間分散した。
【００９３】
更に、この分散液３３０質量部にイソホロンジイソシアネートのブロックタイプのイソシアヌレート型３量体（ＩＰＤＩ）（商品名「ベスタナートＢ１３７０」：デグサ・ヒュルス社製）を２６．３質量部とヘキサメチレンジイソシアネートのイソシアヌレート型３量体（ＨＤＩ）（商品名「デュラネートＴＰＡ−Ｂ８０Ｅ」：旭化成工業（株）製）を１６．９質量部混合し、ボールミルで１時間撹拌し、最後に２００メッシュの網で溶液をろ過して、固形分を４３．８質量％とし、表面層用塗料を得た。
【００９４】
上記塗料を用い、実施例１と同様の条件でディッピング塗布し、乾燥することによって、実施例５の帯電部材を得た。このときの表面層の膜厚は５５μｍであり、電気抵抗は２．９×１０^１０Ωであった。また、この帯電部材の電気抵抗は３．８×１０^６Ωであった。
【００９５】
更に、粘弾性測定の結果、Ｔｇ１＝８０．０℃、Ｔｇ２＝９０．３℃、ΔＴｇ＝１０．３℃で、架橋密度ρ＝９．８×１０^３ｍｏｌ／ｍ^３であった。
【００９６】
実施例５の帯電部材は、Ｈ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置すると６日後に若干端部に軽微なシワが確認され、そのまま７日後までシワの発生は維持されたが、その後の画出し評価でもその部分の画像ムラが少し発生した。
【００９７】
［実施例６］
実施例１と同様にして、導電性支持体上に導電性弾性体層を使用形成した。
【００９８】
次に、ラクトン変性アクリルポリオール（商品名「プラクセルＤＣ２２０９（水酸基価 １２ＫＯＨｍｇ／ｇ）」：ダイセル化学工業（株）製）１４４質量部をＭＩＢＫ（メチルイソブチルケトン）４５６質量部に溶解し、固形分１６．０質量％の溶液とした。このアクリルポリオール溶液２００質量部に対して、前記表面処理導電性酸化錫粉体を３１．２質量部、シリコーンオイル（商品名「ＳＨ−２８ＰＡ」：東レ・ダウコーニングシリコーン（株）製）を０．０１質量部、微粒子シリカ（一次粒子径０．０２μｍ）を０．７２質量部、弾性体粒子（商品名「テクポリマー ＭＢＸ−１２」（平均粒径１２μｍ）：積水化成品工業（株）製）を１８．００質量部、直径０．８ｍｍのガラスビーズを２００質量部加えて、４５０ｍｌのマヨネーズビンに入れ、ペイントシェーカーを使用し、６時間分散した。
【００９９】
更に、この分散液３３０質量部にヘキサメチレンジイソシアネートのイソシアヌレート型３量体（ＨＤＩ）（商品名「デュラネートＴＰＡ−Ｂ８０Ｅ」：旭化成工業（株）製）を６．２質量部混合し、ボールミルで１時間撹拌し、最後に２００メッシュの網で溶液をろ過して、固形分を２９．８質量％とし、表面層用塗料を得た。
【０１００】
上記塗料を用い、実施例１と同様の条件でディッピング塗布し、乾燥することによって、実施例６の帯電部材を得た。このときの表面層の膜厚は２０μｍであり、電気抵抗は３．０×１０^１０Ωであった。また、この帯電部材の電気抵抗は４．１×１０^６Ωであった。
【０１０１】
更に、粘弾性測定の結果、Ｔｇ１＝４２．２℃、Ｔｇ２＝４５．４℃、ΔＴｇ＝３．２℃で、架橋密度ρ＝３．７×１０^６ｍｏｌ／ｍ^３であった。
【０１０２】
実施例６の帯電部材は、Ｈ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置すると４日後に若干端部に軽微なシワが確認され、そのまま７日後までシワの発生は維持されたが、その後の画出し評価でもその部分に相当する箇所に中程度の画像ムラが発生した。
【０１０３】
［比較例１］
実施例１と同様にして、導電性支持体上に導電性弾性体層を形成した。
【０１０４】
次に、ポリエステルポリオール（商品名「キョーワポール１０００ＰＡ（水酸基価 １１２ＫＯＨｍｇ／ｇ）」：協和発酵（株）製）１３７質量部をＭＩＢＫ（メチルイソブチルケトン）４６３質量部に溶解し、固形分１６．０質量％の溶液とした。このポリエステルポリオール溶液２００質量部に対して、前記表面処理導電性酸化錫粉体を４１．６質量部、シリコーンオイル（商品名「ＳＨ−２８ＰＡ」：東レ・ダウコーニングシリコーン（株）製）を０．０１質量部、微粒子シリカ（一次粒子径０．０２μｍ）を１．１４質量部、弾性体粒子（商品名「テクポリマー ＭＢＸ−１２」（平均粒径１２μｍ）：積水化成品工業（株）製）を２４．００質量部、直径０．８ｍｍのガラスビーズを２００質量部加えて、４５０ｍｌのマヨネーズビンに入れ、ペイントシェーカーを使用し、６時間分散した。
【０１０５】
更に、この分散液３３０質量部にイソホロンジイソシアネートのブロックタイプのイソシアヌレート型３量体（ＩＰＤＩ）（商品名「ベスタナートＢ１３７０」：デグサ・ヒュルス社製）を２９．１質量部とヘキサメチレンジイソシアネートのイソシアヌレート型３量体（ＨＤＩ）（商品名「デュラネートＴＰＡ−Ｂ８０Ｅ」：旭化成工業（株）製）を１３．３質量部混合し、ボールミルで１時間撹拌し、最後に２００メッシュの網で溶液をろ過して、固形分を３９．６質量％とし、表面層用塗料を得た。
【０１０６】
上記塗料を用い、実施例１と同様の条件でディッピング塗布し、乾燥することによって、比較例１の帯電部材を得た。このときの表面層の膜厚は２５μｍであり、電気抵抗は２．３×１０^１０Ωであった。また、この帯電部材の電気抵抗は２．８×１０^６Ωであった。
【０１０７】
更に、粘弾性測定の結果、Ｔｇ１＝９０．０℃、Ｔｇ２＝１０８．３℃、ΔＴｇ＝１８．３℃で、架橋密度ρ＝１．２×１０^４ｍｏｌ／ｍ^３であった。
【０１０８】
比較例１の帯電部材は、Ｈ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置すると３日後に若干端部に軽微なシワが確認され、４日後には帯電部材全体にシワの発生し、その後の画出し評価でもその部分に相当する箇所に大きな画像ムラが発生した。
【０１０９】
［比較例２］
実施例１と同様にして、導電性支持体上に導電性弾性体層を形成した。
【０１１０】
次に、水系ポリウレタン（商品名「スーパーフレックス１５０」：第一工業製薬（株）製）２００質量部に対して、前記表面処理導電性酸化錫粉体を７６．０質量部、シリコーンオイル（商品名「ＳＨ−２８ＰＡ」：東レ・ダウコーニングシリコーン（株）製）を０．０１質量部、微粒子シリカ（一次粒子径０．０２μｍ）を３．００質量部、弾性体粒子（商品名「テクポリマー ＭＢＸ−１２」（平均粒径１２μｍ）：積水化成品工業（株）製）を４４．００質量部、直径０．８ｍｍのガラスビーズを２００質量部加えて、４５０ｍｌのマヨネーズビンに入れ、ペイントシェーカーを使用し、６時間分散した。
【０１１１】
上記塗料を用い、実施例１と同様の条件でディッピング塗布し、乾燥することによって、比較例２の帯電部材を得た。このときの表面層の膜厚は３０μｍであり、電気抵抗は３．１×１０^１０Ωであった。また、この帯電部材の電気抵抗は４．５×１０^６Ωであった。
【０１１２】
更に、粘弾性測定の結果、Ｔｇ１＝３７．９℃、Ｔｇ２＝４０．４℃、ΔＴｇ＝２．５℃で、架橋密度ρ＝３．４×１０^２ｍｏｌ／ｍ^３であった。
【０１１３】
比較例２の帯電部材は、Ｈ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置すると３日後には帯電部材全体にシワが発生し、その後の画出し評価でもその部分に相当する箇所に大きな画像ムラが発生した。
【０１１４】
［比較例３］
実施例１と同様にして、導電性支持体上に導電性弾性体層を形成した。
【０１１５】
次に、ポリエステルポリオール（商品名「ＦＬＥＸＯＲＥＺ １８８（水酸基価 ２３０ＫＯＨｍｇ／ｇ）」：楠本化成（株）製）９６質量部をＭＩＢＫ（メチルイソブチルケトン）５０４質量部に溶解し、固形分１６．０質量％の溶液とした。このポリエステルポリオール溶液２００質量部に対して、前記表面処理導電性酸化錫粉体を４１．６質量部、シリコーンオイル（商品名「ＳＨ−２８ＰＡ」：東レ・ダウコーニングシリコーン（株）製）を０．０１質量部、微粒子シリカ（一次粒子径０．０２μｍ）を０．９６質量部、弾性体粒子（商品名「テクポリマー ＭＢＸ−１２」（平均粒径１２μｍ）：積水化成品工業（株）製）を１６．８０質量部、直径０．８ｍｍのガラスビーズを２００質量部加えて、４５０ｍｌのマヨネーズビンに入れ、ペイントシェーカーを使用し、２４時間分散した。
【０１１６】
更に、この分散液３３０質量部にヘキサメチレンジイソシアネートのイソシアヌレート型３量体（ＨＤＩ）（商品名「デュラネートＴＰＡ−Ｂ８０Ｅ」：旭化成工業（株）製）を２７．３質量部混合し、ボールミルで１時間撹拌し、最後に２００メッシュの網で溶液をろ過して、固形分を３９質量％とし、表面層用塗料を得た。
【０１１７】
上記塗料を用い、実施例１と同様の条件でディッピング塗布し、乾燥することによって、比較例２の帯電部材を得た。このときの表面層の膜厚は２０μｍであり、電気抵抗は２．９×１０^１０Ωであった。また、この帯電部材の電気抵抗は３．７×１０^６Ωであった。
【０１１８】
更に、粘弾性測定の結果、Ｔｇ１＝１０６．４℃、Ｔｇ２＝１１２．３℃、ΔＴｇ＝５．９℃で、架橋密度ρ＝２．１×１０^３ｍｏｌ／ｍ^３であった。
【０１１９】
比較例３の帯電部材は、Ｈ／Ｈ環境下で１週間放置後、直ぐにＬ／Ｌ環境に放置すると３日後には帯電部材全体にシワが発生し、その後の画出し評価でもその部分に相当する箇所に大きな画像ムラが発生した。
【０１２０】
以上の評価を表１に示す。
【０１２１】
【表１】

【０１２２】
以上本発明の実施例について説明したが、本発明の好適な実施の態様を以下のとおり列挙する。
【０１２３】
［実施態様１］
導電性支持体上に導電性弾性体層を有し、該導電性弾性体層上に表面層として導電性被覆層を有する帯電部材において、該導電性被覆層の相対湿度８０％におけるガラス転移温度（Ｔｇ１）が４０℃＜Ｔｇ１＜１００℃であり、該導電性被覆層の相対湿度５５％におけるガラス転移温度（Ｔｇ２）と該Ｔｇ１との差ΔＴｇ（＝Ｔｇ２−Ｔｇ１）が３℃＜ΔＴｇ＜１５℃であることを特徴とする帯電部材。
【０１２４】
［実施態様２］
前記ΔＴｇが７℃＜ΔＴｇ＜１５℃である実施態様１に記載の帯電部材。
【０１２５】
［実施態様３］
前記導電性被覆層の架橋密度ρがρ＜１×１０^４ｍｏｌ／ｍ^３である実施態様１または２に記載の帯電部材。
【０１２６】
［実施態様４］
前記導電性被覆層の厚みが１０〜５０μｍである実施態様１〜３のいずれかに記載の帯電部材。
【０１２７】
［実施態様５］
前記導電性被覆層が、平均粒子径が５〜３０μｍの絶縁性粒子を該被覆層の全質量に対し、５〜３０質量％含有する実施態様１〜４のいずれかに記載の帯電部材。
【０１２８】
［実施態様６］
前記絶縁性粒子が架橋タイプのアクリル樹脂またはアクリル／スチレンの共重合樹脂である実施態様５に記載の帯電部材。
【０１２９】
［実施態様７］
前記導電性弾性体層の硬度が、アスカーＣで７０度以上である実施態様１〜６のいずれかに記載の帯電部材。
【０１３０】
［実施態様８］
電子写真感光体、該電子写真感光体に接触配置され、電圧を印加されることにより該電子写真感光体を帯電する実施態様１〜７のいずれかに記載の帯電部材を一体に支持し、電子写真装置本体に着脱自在であることを特徴とするプロセスカートリッジ。
【０１３１】
［実施態様９］
前記帯電部材に印加される電圧が直流電圧のみである実施態様８に記載のプロセスカートリッジ。
【０１３２】
［実施態様１０］
電子写真感光体、該電子写真感光体に接触配置され、電圧を印加されることにより該電子写真感光体を帯電する実施態様１〜７のいずれかに記載の帯電部材、現像手段及び転写手段を具備することを特徴とする電子写真装置。
【０１３３】
［実施態様１１］
前記帯電部材に印加される電圧が直流電圧のみである実施態様１０に記載の電子写真装置。
【０１３４】
【発明の効果】
以上のように、本発明によれば、急激な環境変化による表面性状の変化、つまり表面シワ発生を抑制し、表面性状を制御することで、直流電圧のみを印加する場合でも優れた帯電均一性を確保することができ、画像不良が発生しない帯電部材、かかる帯電部材を用いたプロセスカートリッジ及び電子写真装置装置を提供することができた。
【図面の簡単な説明】
【図１】本発明の帯電部材である帯電ローラの断面の一例を示す概略図である。
【図２】本発明の帯電部材の断面の拡大図である。
【図３】本発明の帯電装置の一例を示す概略図である。
【図４】本発明の帯電部材である帯電ローラ電流値測定装置を示す概略図である。
【符号の説明】
１１ 導電性支持体
１２ 導電性弾性体層
１３ 表面層
１４ 弾性体粒子
２１ 像担持体（電子写真感光体）
２２ 帯電部材（帯電ローラ）
２３ 露光手段
２４ 現像手段
２４ａ トナー担持体
２４ｂ 撹拌部分
２４ｃ トナー規制部材
２５ 転写手段
２６ クリーニング手段
２７ プロセスカートリッジ
３１ 円筒電極（金属ローラ）
３２ 固定抵抗器
３３ 記録計（レコーダー）
Ｌ レーザー光
Ｓ１、Ｓ２、Ｓ３ バイアス印加電源
Ｐ 転写材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is used in a copying machine, a printer, or the like, used to stably charge a latent image holding member such as an electrophotographic photosensitive member used in an electrostatic latent image process, a stable charging member having a surface state of an outermost layer, The present invention relates to a process cartridge and an electrophotographic apparatus having the charging member.
[0002]
[Prior art]
Conventionally, in electrophotographic processes such as copiers and printers, first, the surface of the electrophotographic photosensitive member is uniformly charged, and an image is projected on the photosensitive member from an optical system to erase the charged portion of the light-exposed portion. In this method, a latent image is formed by forming a toner image, a toner image is formed by attaching toner, and then the toner image is transferred to a recording medium such as paper to perform printing. Various rollers for controlling these are used, and in recent years, the required characteristics of the roller material have become increasingly severe.
[0003]
In the electrophotographic process, the step of charging the surface of the photoreceptor has conventionally generally employed a corona discharge method. However, since this corona discharge method requires application of a high voltage of 6 to 10 kV, it is not preferable from the viewpoint of safe maintenance of the machine. Also, ozone and the like generated during corona discharge may adversely affect the photoreceptor.
[0004]
For this reason, charging schemes capable of performing charging with an applied voltage lower than that of corona discharge and suppressing generation of ozone and the like have been undertaken. As an attempt of such a charging method, there has been proposed a contact charging method in which a charged member is charged by applying a voltage to a charging member which is brought into contact with a charged member such as a photoreceptor at a predetermined pressure.
[0005]
However, the contact charging method is somewhat disadvantageous in terms of charging uniformity as compared with the corona charging method.
[0006]
In order to improve the charging uniformity, an AC voltage component (AC voltage component) having a peak-to-peak voltage that is twice or more the charging start voltage (Vth) is superimposed on a DC voltage corresponding to a desired charged body surface potential Vd. An "AC charging method" is used in which a voltage (pulsating voltage: a voltage whose voltage value changes periodically with time) is applied to a contact charging member. This is for the purpose of the effect of leveling the potential by the AC voltage, and the potential of the member to be charged converges to the potential Vd, which is the center of the peak of the AC voltage, and is not affected by disturbances such as the environment. This is an excellent charging method.
[0007]
However, in order to superimpose a high AC voltage which is a peak-to-peak voltage that is twice or more the discharge starting voltage (Vth) when a DC voltage is applied, an AC power supply is required separately from the DC power supply, which increases the cost of the apparatus itself. It becomes a factor. Further, there is a problem that the durability of the charging member and the photoreceptor is easily reduced by consuming a large amount of the alternating current.
[0008]
Although these problems can be solved by performing charging by applying only a DC voltage to the charging member, there are the following problems when only a DC voltage is applied to the charging member.
[0009]
That is, when only a DC voltage is applied to the conventional charging member, uneven charging is likely to occur due to a case where the surface of the member to be charged such as a photosensitive member is charged to a desired charging potential or higher or a potential is insufficient. In particular, in an electrophotographic process without pre-exposure, which is a step for erasing the potential on the photoconductor before primary charging, the potential is likely to occur in the potential portion of the halftone image area.
[0010]
When a halftone image is output by an electrophotographic apparatus using a reversal developing method using a conventional charging member having such a problem, for example, the above-mentioned uneven charging is partially white stripes or white spots on the image. In addition, black streaks, black spots, and roughness occur, and the image quality tends to deteriorate. The occurrence of uneven charging potential tends to occur particularly remarkably at a temperature of 15 ° C. and a relative humidity of 10% RH (hereinafter referred to as an L / L environment).
[0011]
Further, the charging member is stable against various external environment changes, that is, not only in the L / L environment, but also in an environment such as a temperature of 40 ° C. and a relative humidity of 85% RH (hereinafter referred to as an H / H environment). It is desired that the chargeability can be maintained.
[0012]
Further, in order to reduce the environmental dependence of the resistance, the hardness and the coefficient of kinetic friction, and further to prevent contamination and toner adhesion to the photoreceptor, the glass transition temperature is set on a rubber layer having a surface roughness of 0.5 to 10 μm. It describes that a polyurethane resin at 30 to 80 ° C. is coated (for example, see Patent Document 1).
[0013]
[Patent Document 1]
JP-A-9-160354
[0014]
[Problems to be solved by the invention]
However, even in this method, wrinkles may be generated on the surface layer of the charging member due to a difference between swelling due to moisture absorption in an H / H environment and shrinkage due to release of moisture in an L / L environment. Further, in an H / H environment, the elastic modulus is greatly reduced, and the portion in contact with the photoreceptor may be largely permanently deformed.
[0015]
Accordingly, an object of the present invention is to suppress the occurrence of surface wrinkles due to a sudden environmental change, that is, to suppress the occurrence of surface wrinkles, and to control the surface properties, thereby ensuring excellent charging uniformity and preventing image defects. An object of the present invention is to provide a charging member free from generation, a process cartridge provided with the charging member, and an electrophotographic apparatus.
[0016]
[Means for Solving the Problems]
That is, the present invention relates to a charging member having a conductive elastic layer on a conductive support and having a conductive coating layer as a surface layer on the conductive elastic layer, wherein the relative humidity of the conductive coating layer is The glass transition temperature (Tg1) at 80% is 40 ° C. <Tg1 <100 ° C., and the difference ΔTg between the glass transition temperature (Tg2) and the Tg1 at 55% relative humidity of the conductive coating layer (= Tg2−Tg1). Is 3 ° C <ΔTg <15 ° C.
[0017]
Further, the present invention is a process cartridge and an electrophotographic apparatus using such a charging member.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, when the glass transition temperature (Tg1) of the conductive coating layer as the surface layer at a relative humidity of 80% is 40 ° C. or lower, the charging member is easily deformed permanently by pressing against the member to be charged. If the Tg1 is 100 ° C. or higher, the surface layer after curing and shrinking is packed in a rough crosslinked state, so that the moisture permeability becomes too large. More preferably, it is 50 ° C to 90 ° C.
[0019]
When the difference ΔTg (= Tg2−Tg1) between the glass transition temperature (Tg2) and Tg1 at a relative humidity of 55% of the conductive coating layer is 3 ° C. or less, the moisture permeability of the conductive coating layer decreases. In an H / H environment, swelling due to moisture absorption occurs only at the end of the conductive elastic layer of the charging member, and the strain at that portion becomes extremely large. Or it may cause wrinkles. On the other hand, if ΔTg is 15 ° C. or more, a large difference in swelling / shrinkage due to a difference in moisture permeability between the conductive elastic layer and the conductive coating layer is generated, so that it is impossible to cope with a rapid temperature change. Preferably, ΔTg> 7 ° C.
[0020]
The glass transition temperature of the conductive coating layer is affected by the type, structure, compounding amount, reaction point of the binder, and annealing conditions of the resin and the crosslinking agent used. In the present invention, it is important that Tg1 and ΔTg are within the above ranges, and the means for achieving this is not particularly limited, but it is preferable to adjust the type, structure, and amount of the crosslinking agent.
[0021]
Furthermore, in the present invention, when the crosslinked state of the resin in the conductive coating layer is packed in a denser state, the molecular movement of the polymer due to a change in humidity is restricted, and the moisture permeability is also suppressed, and Since the generation of wrinkles can be more effectively prevented, the crosslink density ρ of the resin used is 1 × 10 ⁴ mol / m ³ It is preferably less than. More preferably, 9.8 × 10 ³ mol / m ³ It is as follows.
[0022]
The cross-linking state of the resin is affected by the type of the monomer and the cross-linking agent of the resin, their quantitative ratio, curing conditions such as temperature and time, and annealing conditions. In the present invention, it is important that ρ is within the above range, and the means for achieving ρ is not particularly limited, but is preferably adjusted under curing conditions.
[0023]
FIG. 1 is a schematic view showing an example of a cross section of a charging roller as a charging member of the present invention as a structure and a form of the charging member of the present invention. The charging roller in the figure has a conductive elastic layer 12 on the outer periphery of a conductive support (shaft) 11, and has a conductive coating layer 13 as a surface layer outside the conductive elastic layer 12. ing.
[0024]
The conductive elastic layer 12 can be formed of a solid body such as rubber or thermoplastic elastomer conventionally used as an elastic layer of a charging member. Specifically, a rubber having a base rubber such as polyurethane, silicone rubber, butadiene rubber, isoprene rubber, chloroprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, and epichlorohydrin rubber There are no particular restrictions on the type of the composition or the thermoplastic elastomer, and one or more thermoplastic elastomers selected from general-purpose styrene-based elastomers and olefin-based elastomers can be suitably used.
[0025]
Commercially available styrene elastomers include, for example, "Lavalon" manufactured by Mitsubishi Chemical Corporation and "Septon Compound" manufactured by Kuraray Co., Ltd. Commercially available olefin-based elastomers include, for example, "Thermolan" manufactured by Mitsubishi Chemical Corporation, "Milastomer" manufactured by Mitsui Petrochemical Industry Co., Ltd., "Sumitomo TPE" manufactured by Sumitomo Chemical Co., Ltd., and It can be obtained from the market as "Santoprene" manufactured by Advanced Elastomer Systems.
[0026]
A predetermined conductivity can be imparted to the conductive elastic layer 12 by adding a conductive agent. The conductive agent is not particularly limited, and may be lauryl trimethyl ammonium, stearyl trimethyl ammonium, octadodecyl trimethyl ammonium, dodecyl trimethyl ammonium, hexadecyl trimethyl ammonium, or a perchlorate, chlorate or fluorinated salt of a modified fatty acid / dimethylethyl ammonium. Cationic surfactants such as quaternary ammonium salts such as hydride salts such as hydride salts, ethosulfate salts, benzyl bromide salts and benzyl chloride salts, aliphatic sulfonates, higher alcohol sulfates , Anionic surfactants such as higher alcohol ethylene oxide addition sulfates, higher alcohol phosphates and higher alcohol ethylene oxide addition phosphates, and zwitterionic surfactants such as various betaines; Alcohol ethylene oxide, polyethylene glycol fatty acid esters and antistatic agents such as nonionic antistatic agents such as polyhydric alcohol fatty acid esters, LiCF ₃ SO ₃ , NaClO ₄ , LiAsF ₆ , LiBF ₄ , NaSCN, KSCN and Li such as NaCl ⁺ , Na ⁺ And K ⁺ Electrolytes such as metal salts or quaternary ammonium salts of Group 1 of the periodic table, such as Ca (ClO) ₄ ) ₂ Ca such as ²⁺ And Ba ²⁺ The metal salts of Group 2 of the Periodic Table and those having an antistatic agent having at least one group having an active hydrogen which reacts with isocyanate such as a hydroxyl group, a carboxyl group and a primary or secondary amine group. Is mentioned. Further, they are complexed with polyhydric alcohols such as 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol and polyethylene glycol and derivatives thereof, or monools such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether. An ion conductive agent such as a complex with, or a conductive carbon such as Ketjen Black EC and acetylene black, or Super Abrasion Furnace (SAF super abrasion resistance), Intermediate Super Abrasion Furnace (ISAF semi-super abrasion resistance), High Abrasion Furnace (HAF high abrasion resistance), Fast Extruding Furnace (FEF good extrudability), Genera Carbon for rubber such as Purpose Furnace (general versatility of GPF), Semi Reinforcing Furnace (reinforcing in SRF), Fine Thermal (FT fine pyrolysis) and Medium Thermal (MT medium pyrolysis), etc., and oxidized color (ink) ) Carbon, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped metals such as tin oxide, titanium oxide, zinc oxide, nickel, copper, silver and germanium, and metal oxides, or conductive materials such as polyaniline, polypyrrole and polyacetylene. Polymer and the like.
[0027]
The amount of these conductive agents is appropriately selected according to the type of the composition, and the electric resistance of the conductive elastic layer 12 is preferably 10 ² -10 ⁸ Ω, more preferably 10 ³ -10 ⁶ It is adjusted to be Ω.
[0028]
In the present invention, the hardness of the conductive elastic layer is preferably 70 degrees or more, and particularly preferably 73 degrees or more in Asker C. The upper limit of the hardness is preferably 95 degrees or less. If the hardness is less than 70 degrees, the amount of deformation at the time of contact with the member to be charged becomes large, so that the amount of permanent deformation at the contact portion tends to be large. Conversely, when the hardness exceeds 95 degrees, it is difficult to obtain uniform contact with the member to be charged.
[0029]
Preferred resins contained in the conductive coating layer 13 include polyester resin, acrylic resin, urethane resin, acryl-modified urethane resin, urethane-modified acrylic resin, nylon resin, epoxy resin, polyvinyl acetal resin, vinylidene chloride resin, fluorine resin and Examples thereof include a silicone resin and the like, and any of an organic type and an aqueous type can be used. Among these, a crosslinkable resin such as an acrylic resin, a urethane resin, an acrylic-modified urethane resin, a urethane-modified acrylic resin, an epoxy resin, a fluororesin, and a silicone resin are preferable, and a urethane-modified acrylic resin is particularly preferable.
[0030]
Further, an appropriate amount of an additive such as a crosslinking agent can be added to the conductive coating layer as needed in order to control the crosslinking density. In this case, any crosslinking agent may be used as long as the desired crosslinking effect can be obtained. For example, epoxy-based, oxazoline-based, melamine-based, isocyanate-based, and phenol-based crosslinking agents can be exemplified.
[0031]
The conductive coating layer 13 may be added or adjusted with a conductive agent by adding a conductive agent. In this case, the conductive agent is not particularly limited, but may be Ketjen Black EC or acetylene black. Conductive carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT and MT, etc., carbon for oxidation (carbon) for color (ink), pyrolytic carbon, natural graphite, artificial graphite, antimony Metals such as doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium, and metal oxides can be used.
[0032]
Further, when the conductive agent is used in an organic solvent, it is preferable that the surface of the conductive agent is subjected to a surface treatment such as a silane coupling treatment in consideration of dispersibility.
[0033]
Further, the amount of the conductive agent to be added can be appropriately adjusted so as to obtain a desired resistance. In this case, the resistance of the conductive coating layer 13 is the electric resistance 10 ¹ -10 ¹² Ω, especially 10 ³ -10 ¹¹ Ω is preferable, the amount of the conductive agent can be adjusted to achieve such a volume resistivity, and antimony-doped tin oxide surface-treated with a silane coupling agent is used as the conductive agent. When used, the amount of addition is preferably 0.01 to 30% by mass of the total mass of the conductive coating layer 13, and particularly preferably about 5 to 20% by mass.
[0034]
The electric resistance as a charging member is 10 ³ -10 ¹⁰ Ω, especially 10 ⁵ -10 ⁸ Ω is preferred.
[0035]
In the present invention, it is preferable to add elastic particles to the conductive coating layer 13 for the purpose of improving charging uniformity. FIG. 2 is a sectional view of the charging member in that case. Examples of the elastic particles 14 include inorganic particles that are insulating particles other than the conductive agent, such as calcium carbonate, clay, talc, and silica. Examples of the insulating organic particles include acrylic resin, acrylic / styrene copolymer resin, polyamide resin, silicone rubber particles, and epoxy resin particles. Among them, acrylic resin or acrylic / styrene copolymer as organic particles are included. Polymer resins are particularly preferred because they do not significantly change the stiffness of the surface layer. Further, when organic particles are used, it is preferable to use a crosslinked type so that the particles are not swollen in combination with the solvent used and the particle shape is not changed.
[0036]
The average particle diameter of such elastic particles is preferably 5 to 30 μm, and particularly preferably 8 to 20 μm. The average particle size is measured as follows.
[0037]
That is, using a Coulter Counter Multisizer II (manufactured by Coulter) as a measuring device, an interface (manufactured by Nikkaki) for outputting a number distribution and a volume distribution and a CX-1 personal computer (manufactured by Canon) were connected, and an electrolytic solution was used. Prepares a 1% NaCl aqueous solution using special grade or primary grade sodium chloride. As a measurement method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample is suspended is subjected to dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and the measurement is performed by using a 100 μm aperture as an aperture with the Multisizer II of the Coulter Counter. If the average particle diameter is less than 5 μm, it is difficult to improve the charging uniformity. If the average particle diameter exceeds 30 μm, the surface of the charging member is liable to be stained by a toner external additive after durability.
[0038]
Further, the content of the elastic particles is preferably 5 to 30% by mass, more preferably 8 to 20% by mass, based on the total mass of the conductive coating layer. When the content is less than 5% by mass, it is difficult to obtain the effect of improving the charging uniformity due to the addition of the particles, and when the content exceeds 30% by mass, black spots on an image tend to be caused.
[0039]
In addition, in FIG. 2, 12 and 13 show the same thing as FIG. 1, respectively.
[0040]
Further, in the present invention, the thickness of the conductive coating layer 13 is preferably from 10 to 50 μm, and particularly preferably from 10 to 30 μm. When the thickness is less than 10 μm, it becomes difficult to prevent substances bleeding from the conductive elastic layer, and when the thickness is more than 50 μm, the conductive coating layer 13 becomes hard and the flexibility is impaired. And the durability is reduced, and cracks are likely to occur with use.
[0041]
The method of forming the conductive coating layer 13 is not particularly limited, but a method of preparing a paint containing each component and applying the paint by dipping or spraying to form a coating film is preferably used. Can be In this case, when a plurality of conductive coating layers are provided, dipping and spraying may be repeated using a paint for forming each layer. Note that the conductive coating layer is preferably formed by the above dipping method or spray method.
[0042]
In the present invention, an intermediate layer for the purpose of enhancing the adhesiveness between the conductive elastic layer 12 and the conductive support 11 or between the conductive elastic layer 12 and the conductive coating layer 13 is formed. It can also be provided.
[0043]
FIG. 3 shows an example in which a process cartridge using the charging member of the present invention is applied to an electrophotographic apparatus. Reference numeral 21 denotes a rotating drum type electrophotographic photosensitive member (photosensitive member) as an image carrier. The photoconductor 21 is driven to rotate at a predetermined peripheral speed (process speed) clockwise as indicated by an arrow in the drawing. As the photoconductor 21, for example, a known photoconductor having at least a roll-shaped conductive support and a photosensitive layer containing an inorganic photosensitive material or an organic photosensitive material on the support may be adopted. Further, the photoconductor 21 may further include a charge injection layer for charging the photoconductor surface to a predetermined polarity and potential.
[0044]
Reference numeral 22 denotes a charging roller (conductive roller) as a charging member. A charging unit is constituted by the charging roller 22 and a charging bias application power supply S1 for applying a charging bias to the charging roller 22. The charging roller 22 is brought into contact with the photoconductor 21 with a predetermined pressing force, and in this example, is driven to rotate in the forward direction with respect to the rotation of the photoconductor 21. When a predetermined DC voltage (-1200 V in this example) is applied to the charging roller 22 from the charging bias application power supply S1 (in this example, -1200 V), the surface of the photoconductor 21 has a predetermined polarity potential ( In this example, the charging process is performed uniformly at a dark portion potential of −600 V).
[0045]
23 is an exposure means. A known means can be used as the exposure means 23, and a laser beam scanner or the like can be preferably exemplified. L is exposure light.
[0046]
Image exposure corresponding to the target image information is performed on the charged surface of the photoreceptor 21 by the exposing means 23, and thereby the potential of the exposed light portion of the charged surface of the photoreceptor (the light portion potential is -350V in this example). Is selectively reduced (attenuated), and an electrostatic latent image is formed on the photoconductor 21.
[0047]
24 is a reversal developing means. As the developing unit 24, a known unit can be used. For example, the developing unit 24 in the present embodiment includes a toner carrier 24 a that is disposed at an opening of a developing container that stores toner and carries and transports toner. And a toner regulating member 24c that regulates the amount (toner layer thickness) of the toner carried on the toner carrier 24a. The developing unit 24 selectively attaches a toner (negative toner) charged to the same polarity as the charged polarity of the photoconductor 21 on the exposed light portion of the electrostatic latent image on the surface of the photoconductor 21 to form an electrostatic latent image. It is visualized as a toner image (in this example, the developing bias is -350 V). There is no particular limitation on the developing method, and all existing methods can be used. Existing methods include, for example, a jumping development method, a contact development method, a magnetic brush method, and the like. Particularly, in an image forming apparatus that outputs a color image, a contact development method is used for the purpose of improving toner scattering. Is preferable.
[0048]
Reference numeral 25 denotes a transfer roller as transfer means. As the transfer roller 25, known means can be used, and examples thereof include a transfer roller formed by coating a conductive support such as a metal with an elastic resin layer adjusted to have a medium resistance. The transfer roller 25 is brought into contact with the photoconductor 21 with a predetermined pressing force, and rotates at a peripheral speed substantially equal to the rotation peripheral speed of the photoconductor 21 in a forward direction with the rotation of the photoconductor 21. Further, a transfer voltage having a polarity opposite to the charging characteristic of the toner is applied from the transfer bias applying power source S2. A transfer material P is fed from a paper feed mechanism (not shown) to a contact portion between the photoconductor 21 and the transfer roller at a predetermined timing, and the back surface of the transfer material P is charged by a transfer roller 25 to which a transfer voltage is applied. The toner image on the surface of the photoconductor 21 is electrostatically transferred to the surface of the transfer material P at the contact portion between the photoconductor 21 and the transfer roller.
[0049]
The transfer material P to which the toner image has been transferred is separated from the photoreceptor surface, introduced to a toner image fixing unit (not shown), and fixed to the toner image to be output as an image formed product. In the case of the double-sided image forming mode or the multiple image forming mode, this image-formed product is introduced into a recirculating transport mechanism (not shown) and is re-introduced into the transfer section.
[0050]
Residues on the photoreceptor 21 such as transfer residual toner are collected from the photoreceptor by cleaning means 26 such as a blade type.
[0051]
If residual charges remain on the photoconductor 21, it is better to remove the residual charges on the photoconductor 21 by a pre-exposure device (not shown) after the transfer and before performing the primary charging by the charging member 22. .
[0052]
The process cartridge of the present invention has a structure in which at least the charging member 22 and the photosensitive member 21 are integrally supported, and is detachable from the main body of the electrophotographic apparatus. In FIG. 3, a process cartridge 27 is formed by integrally supporting the charging member 22, the photosensitive member 21, the developing unit 24, and the cleaning unit 26.
[0053]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following.
[0054]
[Example 1]
(Formation of conductive elastic layer)
100 parts by mass of epichlorohydrin rubber (trade name “Epichromer CG102”: manufactured by Daiso Co., Ltd.), 30 parts by mass of calcium carbonate as a filler, colored grade carbon as a reinforcing material for improving abrasiveness (trade name “SEIST SO”) : Tokai Carbon) 2 parts by mass, zinc oxide 5 parts by mass, plasticizer (DOP: dioctyl phthalate) 10 parts by mass, perchloric acid quaternary ammonium salt having the following structure 3 parts by mass
[0055]
Embedded image

And 1 part by mass of an antioxidant (2-mercaptobenzimidazole) are kneaded with an open roll for 20 minutes, further 1 part by mass of a vulcanization accelerator (DM) and 1 part by mass of a vulcanization accelerator (TS: Tetramethylthiurammonosulfide). 5 parts by mass and 1 part by mass of sulfur as a vulcanizing agent were added, and the mixture was further kneaded with an open roll for 15 minutes.
[0056]
The obtained kneaded material was extruded into a cylindrical shape having an outer diameter of 15 mm and an inner diameter of 5.5 mm by a rubber extruder, cut into a length of 250 mm, and subjected to primary vulcanization with steam at 160 ° C. for 40 minutes in a vulcanizer, A conductive elastic layer primary vulcanized tube was obtained.
[0057]
Next, a thermosetting adhesive of metal and rubber (trade name: 231 mm) was applied to the center 231 mm in the axial direction of the cylindrical surface of the cylindrical conductive support (steel, industrial nickel plating) having a diameter of 6 mm and a length of 256 mm. Metallok U-20) was applied, dried at 80 ° C. for 30 minutes, and further dried at 120 ° C. for 1 hour. This support was inserted into the primary vulcanization tube of the conductive elastic layer, and then subjected to secondary vulcanization and curing of the adhesive at 160 ° C. for 2 hours using an electric oven to obtain an unpolished product. . After cutting both ends of the rubber portion of this unpolished product to make the length of the rubber portion 231 mm, the rubber portion is polished with a rotary grindstone, and the surface is formed in a crown shape having an end diameter of 9.7 mm and a central portion of 10.0 mm. A charging member having a conductive elastic layer having a ten-point average roughness (Rz) of 7 μm and a run-out of 25 μm was obtained.
[0058]
The charging member having the conductive elastic layer was left in an N / N (normal temperature and normal humidity: 23 ° C., 55% RH) environment for 24 hours, and a cylindrical electrode (metal roller) 31, a fixed resistor 32, When the resistance of the conductive elastic layer was measured at an applied voltage of 200 V by a current value measuring device including a recorder (recorder) 33 and the like, 1.9 × 10 ⁵ Ω. The hardness was 74 degrees (Asker C).
[0059]
(Formation of surface layer (conductive coating layer))
500 parts by mass of a 1% isopropyl alcohol solution of trifluoropropyltrimethoxysilane was added to 50 parts by mass of conductive tin oxide powder (trade name “SN-100P”: manufactured by Ishihara Sangyo Co., Ltd.) and the average particle diameter was 0.8 mm. After adding 300 parts by mass of glass beads and dispersing with a paint shaker for 70 hours, the dispersion was filtered through a 500-mesh net, and then the solution was warmed in a hot water bath at 100 ° C. while stirring with a Nauta mixer to remove alcohol. And dried to give a silane coupling agent on the surface to obtain a surface-treated conductive tin oxide.
[0060]
Further, 137 parts by mass of a lactone-modified acrylic polyol (trade name “Placcel DC2016 (hydroxyl value: 80 KOH mg / g)”: manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 463 parts by mass of MIBK (methyl isobutyl ketone) to obtain a solid content of 16.3 parts. The solution was 0% by mass. 41.6 parts by mass of the surface-treated conductive tin oxide powder and 0 parts of silicone oil (trade name “SH-28PA” manufactured by Dow Corning Toray Silicone Co., Ltd.) were added to 200 parts by mass of this acrylic polyol solution. 0.01 parts by mass, 0.96 parts by mass of fine-particle silica (primary particle size 0.02 μm), elastic particles (trade name “Techpolymer MBX-12” (average particle size 12 μm): manufactured by Sekisui Plastics Co., Ltd.) ) Was added to 200 parts by mass of glass beads having a diameter of 0.8 mm and placed in a 450 ml mayonnaise bottle, and dispersed using a paint shaker for 6 hours.
[0061]
Further, 23.3 parts by mass of a block type isocyanurate-type trimer (IPDI) (trade name “Vestanat B1370”, manufactured by Degussa Hüls) and 330 parts by mass of the isocyanate of hexamethylene diisocyanate were added to 330 parts by mass of the dispersion. 14.9 parts by mass of a nurate type trimer (HDI) (trade name “Duranate TPA-B80E”: manufactured by Asahi Kasei Kogyo Co., Ltd.) was mixed, stirred for 1 hour by a ball mill, and finally, the solution was passed through a 200 mesh net. After filtration, the solid content was adjusted to 39% by mass to obtain a coating material for a surface layer.
[0062]
The paint for the surface layer was applied to the surface of the charging member having the conductive elastic layer by a dipping method. Coating was performed at a lifting speed of 400 mm / min, air-dried for 30 minutes, the axis direction was reversed, coating was performed again at a lifting speed of 400 mm / min, air-dried for 30 minutes, and dried at 160 ° C. for 1 hour using an oven. At this time, the film thickness was 25 μm. The electric resistance of this surface layer is 3.9 × 10 ¹⁰ Ω. When the electric resistance of the charging member was measured in the same manner as in the case of the conductive elastic layer, it was 5.0 × 10 ⁶ Ω.
[0063]
The viscoelasticity measurement of the surface layer is performed by applying a paint similar to the paint for the surface layer of the charging member on a 75 μm-thick aluminum sheet with a bar coater and drying in the same manner as when the surface layer of the charging member is formed. A film having a thickness of about 50 μm was formed, and the obtained sample was measured by using an itk DVA-220 dynamic viscoelasticity measurement device (IT Measurement Control Co., Ltd.). The measurement of Tg1 was performed at a constant humidity of 80% RH (under a nitrogen atmosphere), a temperature rising rate of 4 ° C./min, a frequency of 10 Hz, and a tensile mode. Similarly, Tg2 was carried out in a normal atmosphere (humidity 55% RH, under a nitrogen atmosphere), at a heating rate of 4 ° C./min, at a frequency of 10 Hz, and in a tensile mode. The sample of Example 1 had Tg1 = 80.0 ° C., Tg2 = 90.3 ° C., and ΔTg = 10.3 ° C.
[0064]
Further, in order to calculate the crosslink density, the following equation was used by using the storage elastic modulus E ′ of the rubbery region of the viscoelastic property under the above-mentioned normal atmosphere.
[0065]
ρ (E ') = E _R '/ 3RT
(Where E _R 'Indicates the storage modulus in the rubber region, R indicates the gas constant, and T indicates the absolute temperature. )
[0066]
Here, the value of Tg + 40 ° C. was used for E ′. The crosslink density ρ of the surface layer of Example 1 was 9.8 × 10 ³ mol / m ³ Met.
[0067]
(Observation of the surface layer of the charging member)
The charging member obtained as described above was allowed to stand in an H / H environment for one week and then immediately left in an L / L environment, and its surface condition was visually checked every day for one week. A sample having no wrinkles on the surface was evaluated as ○, a sample slightly wrinkled at the end was evaluated as Δ, and a sample wrinkled on the entire charging member was evaluated as ×.
[0068]
(Evaluation of image)
Using the charging member obtained as described above, image evaluation was performed as described below.
[0069]
The electrophotographic laser printer used in this test was a reversal development type A4 vertical output machine equipped with a process cartridge having a charging member and a photoreceptor integrally. The output speed of the recording medium was 94 mm / sec. The image resolution is 600 dpi.
[0070]
The photosensitive member is a photosensitive drum in which an OPC layer having a thickness of 18 μm is coated on an aluminum cylinder, and the outermost layer is a charge transport layer using modified polycarbonate as a binder resin. The toner was prepared by polymerizing a random copolymer of styrene and butyl acrylate containing a charge control agent, a dye and the like mainly with wax, further polymerizing a thin polyester layer on the surface, and externally adding silica fine particles. The toner has a glass transition temperature of 63 ° C. and a volume average particle diameter of 6 μm.
[0071]
All image evaluations were performed in a low-temperature and low-humidity environment (L / L: 15 ° C., 10% RH), and A4 halftone (an image in which a horizontal line with a width of 1 dot and a spacing of 2 dots was drawn in the direction perpendicular to the rotation direction of the photoconductor) An image was output, and whether or not charging unevenness caused by surface wrinkles of the charging member occurred was visually observed. ◎ indicates that no charging unevenness occurred, ○ indicates that slight occurrence occurred, Δ indicates medium occurrence, and X indicates extremely unevenness.
[0072]
The charging member of Example 1 has no wrinkles on its surface even if left immediately in an L / L environment after being left for one week in an H / H environment. There was no occurrence and there was no problem at all.
[0073]
[Example 2]
In the same manner as in Example 1, a conductive elastic layer was formed on a conductive support.
[0074]
Next, 144 parts by mass of a lactone-modified acrylic polyol (trade name “Placcel DC2209 (hydroxyl value: 12 KOH mg / g)”: manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 456 parts by mass of MIBK (methyl isobutyl ketone) to obtain a solid content of 16%. A solution of 0.0% by mass was obtained. 31.2 parts by mass of the surface-treated conductive tin oxide powder and 0 parts of silicone oil (trade name “SH-28PA”: Dow Corning Toray Silicone Co., Ltd.) were added to 200 parts by mass of this acrylic polyol solution. 0.01 parts by mass, 0.72 parts by mass of fine-particle silica (primary particle size 0.02 μm), elastic particles (trade name “Techpolymer MBX-12” (average particle size 12 μm): manufactured by Sekisui Plastics Co., Ltd.) ) And 200 parts by weight of glass beads having a diameter of 0.8 mm were added to a 450 ml mayonnaise bottle, and dispersed using a paint shaker for 6 hours.
[0075]
Further, 4.8 parts by mass of a block type isocyanurate-type trimer (IPDI) (trade name “Vestanat B1370”, manufactured by Degussa Huls Co.) and 330 parts by mass of the isocyanate of hexamethylene diisocyanate were added to 330 parts by mass of this dispersion. 3.1 parts by mass of a nurate-type trimer (HDI) (trade name “Duranate TPA-B80E”: manufactured by Asahi Kasei Kogyo Co., Ltd.) is mixed, stirred by a ball mill for 1 hour, and finally, the solution is passed through a 200 mesh net. After filtration, the solid content was adjusted to 30% by mass to obtain a surface layer paint.
[0076]
The above-mentioned paint was dipped and applied under the same conditions as in Example 1 and dried to obtain a charging member of Example 2. At this time, the thickness of the surface layer was 30 μm, and the electric resistance was 2.7 × 10 ¹⁰ Ω. The electric resistance of the charging member was 3.5 × 10 ⁶ Ω.
[0077]
Furthermore, as a result of viscoelasticity measurement, Tg1 = 50.9 ° C., Tg2 = 58.3 ° C., ΔTg = 7.4 ° C., and the crosslink density ρ = 9.3 × 10 ³ mol / m ³ Met.
[0078]
The charging member of Example 2 had no wrinkles on its surface even if left immediately in an L / L environment after being left for one week in an H / H environment, and even after image evaluation, image unevenness was observed. There was no occurrence and there was no problem at all.
[0079]
[Example 3]
In the same manner as in Example 1, a conductive elastic layer was formed on a conductive support.
[0080]
Next, 137 parts by mass of a lactone-modified acrylic polyol (trade name “Placcel DC2009 (hydroxyl value: 90 KOHmg / g)”: manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 463 parts by mass of MIBK (methyl isobutyl ketone) to obtain a solid content of 16%. A solution of 0.0% by mass was obtained. 31.2 parts by mass of the surface-treated conductive tin oxide powder and 0 parts of silicone oil (trade name “SH-28PA”: Dow Corning Toray Silicone Co., Ltd.) were added to 200 parts by mass of this acrylic polyol solution. 0.01 parts by mass, 0.96 parts by mass of fine-particle silica (primary particle size 0.02 μm), elastic particles (trade name “Techpolymer MBX-12” (average particle size 12 μm): manufactured by Sekisui Plastics Co., Ltd.) ) And 200 parts by mass of glass beads having a diameter of 0.8 mm were added to a 450 ml mayonnaise bottle, and dispersed in a paint shaker for 6 hours.
[0081]
Furthermore, a blocked isocyanate (trade name "Coronate 2520", manufactured by Nippon Polyurethane Co., Ltd.) in which 330 parts by mass of this dispersion is a PPG (polypropylene ether glycol) main chain and both ends are blocked with polymeric MDI (diphenylmethane diisocyanate) with MEK (methyl ethyl ketone) oxime ) And 15.1 parts by mass of an isocyanurate-type trimer of hexamethylene diisocyanate (HDI) (trade name “Duranate TPA-B80E”: manufactured by Asahi Kasei Kogyo Co., Ltd.), and 14.1 parts by mass of the mixture were mixed with a ball mill. The mixture was stirred for an hour, and finally, the solution was filtered through a 200-mesh net to make the solid content 41.5% by mass to obtain a coating for a surface layer.
[0082]
Using the above-mentioned paint, dipping was applied under the same conditions as in Example 1 and dried to obtain a charging member of Example 3. At this time, the thickness of the surface layer was 25 μm, and the electric resistance was 3.2 × 10 ¹⁰ Ω. The electrical resistance of this charging member was 4.6 × 10 ⁶ Ω.
[0083]
Further, as a result of viscoelasticity measurement, Tg1 = 67.9 ° C., Tg2 = 76.3 ° C., ΔTg = 8.4 ° C., and crosslink density ρ = 5.6 × 10 ³ mol / m ³ Met.
[0084]
The charging member of Example 3 was left in an H / H environment for one week and then immediately left in an L / L environment without any wrinkles on its surface. There was no occurrence and there was no problem at all.
[0085]
[Example 4]
In the same manner as in Example 1, a conductive elastic layer was formed on a conductive support.
[0086]
Next, 137 parts by mass of a lactone-modified acrylic polyol (trade name “Placcel DC2009 (hydroxyl value: 90 KOHmg / g)”: manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 463 parts by mass of MIBK (methyl isobutyl ketone) to obtain a solid content of 16%. A solution of 0.0% by mass was obtained. 41.6 parts by mass of the surface-treated conductive tin oxide powder and 0 parts of silicone oil (trade name “SH-28PA” manufactured by Dow Corning Toray Silicone Co., Ltd.) were added to 200 parts by mass of this acrylic polyol solution. 0.01 parts by mass, 0.96 parts by mass of fine-particle silica (primary particle size 0.02 μm), elastic particles (trade name “Techpolymer MBX-12” (average particle size 12 μm): manufactured by Sekisui Plastics Co., Ltd.) ) Was added to 200 parts by mass of glass beads having a diameter of 0.8 mm and placed in a 450 ml mayonnaise bottle, and dispersed using a paint shaker for 6 hours.
[0087]
In addition, 15.3 parts by mass of a blocked isocyanate (trade name "Coronate 2516", manufactured by Nippon Polyurethane Co., Ltd.) obtained by blocking unmodified polymeric MDI with MEK oxime was added to 330 parts by mass of this dispersion, and isocyanurate-type triammonium hexamethylene diisocyanate was used. 16.5 parts by mass of a solid (HDI) (trade name “Duranate TPA-B80E”: manufactured by Asahi Kasei Kogyo Co., Ltd.), stirred for 1 hour with a ball mill, and finally filtered the solution with a 200 mesh net. The solid content was set to 40.0% by mass to obtain a paint for a surface layer.
[0088]
The charging member of Example 4 was obtained by dipping and drying the same coating material as in Example 1 under the same conditions as in Example 1. At this time, the thickness of the surface layer was 18 μm, and the electric resistance was 4.0 × 10 4. ¹⁰ Ω. The electric resistance of this charging member is 5.1 × 10 ⁶ Ω.
[0089]
Further, as a result of viscoelasticity measurement, Tg1 = 69.8 ° C., Tg2 = 82.2 ° C., ΔTg = 12.4 ° C., and crosslink density ρ = 8.8 × 10 ³ mol / m ³ Met.
[0090]
When the charging member of Example 4 was left under the H / H environment for one week and immediately left in the L / L environment, slight wrinkles were slightly observed at the end after 7 days. Some image unevenness occurred in that part.
[0091]
[Example 5]
In the same manner as in Example 1, a conductive elastic layer was formed on a conductive support.
[0092]
Also, 163 parts by mass of a lactone-modified acrylic polyol (trade name “Placcel DC2016 (hydroxyl value: 80 KOH mg / g)”: manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 437 parts by mass of MIBK (methyl isobutyl ketone), and the solid content was 19. The solution was 0% by mass. For 200 parts by mass of this acrylic polyol solution, 49.4 parts by mass of the surface-treated conductive tin oxide powder and 0 parts of silicone oil (trade name “SH-28PA”: manufactured by Dow Corning Toray Silicone Co., Ltd.) were added. 0.01 parts by mass, 1.14 parts by mass of fine-particle silica (primary particle size: 0.02 μm), elastic particles (trade name “Techpolymer MBX-12” (average particle size: 12 μm): manufactured by Sekisui Plastics Co., Ltd.) ) Was added, and 200 parts by mass of glass beads having a diameter of 0.8 mm were added. The mixture was placed in a 450 ml mayonnaise bottle, and dispersed using a paint shaker for 6 hours.
[0093]
Further, 23.3 parts by mass of a block type isocyanurate-type trimer (IPDI) (trade name “Vestanat B1370”, manufactured by Degussa Hüls) and 330 mass parts of isocyanate of hexamethylene diisocyanate were added to 330 parts by mass of this dispersion. 16.9 parts by mass of a nurate type trimer (HDI) (trade name “Duranate TPA-B80E”: manufactured by Asahi Kasei Kogyo Co., Ltd.) was mixed, stirred for 1 hour by a ball mill, and finally, the solution was passed through a 200 mesh net. After filtration, the solid content was adjusted to 43.8% by mass to obtain a surface layer paint.
[0094]
The charging member of Example 5 was obtained by dipping and drying under the same conditions as in Example 1 using the above paint. At this time, the thickness of the surface layer was 55 μm, and the electrical resistance was 2.9 × 10 ¹⁰ Ω. The electric resistance of this charging member is 3.8 × 10 ⁶ Ω.
[0095]
Further, as a result of viscoelasticity measurement, Tg1 = 80.0 ° C., Tg2 = 90.3 ° C., ΔTg = 10.3 ° C., and crosslink density ρ = 9.8 × 10 ³ mol / m ³ Met.
[0096]
When the charging member of Example 5 was left in an H / H environment for one week and then immediately left in an L / L environment, a slight wrinkle was confirmed at the end after 6 days, and the generation of wrinkles was maintained until 7 days after that. However, in the subsequent image evaluation, a little image unevenness of the portion occurred.
[0097]
[Example 6]
In the same manner as in Example 1, a conductive elastic layer was formed on a conductive support.
[0098]
Next, 144 parts by mass of a lactone-modified acrylic polyol (trade name “Placcel DC2209 (hydroxyl value: 12 KOH mg / g)”: manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 456 parts by mass of MIBK (methyl isobutyl ketone) to obtain a solid content of 16%. A solution of 0.0% by mass was obtained. 31.2 parts by mass of the surface-treated conductive tin oxide powder and 0 parts of silicone oil (trade name “SH-28PA”: Dow Corning Toray Silicone Co., Ltd.) were added to 200 parts by mass of this acrylic polyol solution. 0.01 parts by mass, 0.72 parts by mass of fine-particle silica (primary particle size 0.02 μm), elastic particles (trade name “Techpolymer MBX-12” (average particle size 12 μm): manufactured by Sekisui Plastics Co., Ltd.) ) And 200 parts by weight of glass beads having a diameter of 0.8 mm were added to a 450 ml mayonnaise bottle, and dispersed using a paint shaker for 6 hours.
[0099]
Further, to 330 parts by mass of this dispersion, 6.2 parts by mass of isocyanurate-type trimer of hexamethylene diisocyanate (HDI) (trade name “Duranate TPA-B80E”: manufactured by Asahi Kasei Kogyo Co., Ltd.) was mixed, and the mixture was mixed with a ball mill. The mixture was stirred for 1 hour, and finally, the solution was filtered through a 200-mesh net to make the solid content 29.8% by mass, to obtain a surface layer coating material.
[0100]
The charging member of Example 6 was obtained by using the above-mentioned paint and dipping and drying it under the same conditions as in Example 1. At this time, the thickness of the surface layer was 20 μm, and the electric resistance was 3.0 × 10 3 ¹⁰ Ω. The electrical resistance of this charging member was 4.1 × 10 ⁶ Ω.
[0101]
Further, as a result of viscoelasticity measurement, Tg1 = 42.2 ° C., Tg2 = 45.4 ° C., ΔTg = 3.2 ° C., and crosslink density ρ = 3.7 × 10 ⁶ mol / m ³ Met.
[0102]
When the charging member of Example 6 was left in an H / H environment for one week and then immediately left in an L / L environment, a slight wrinkle was observed at the end after 4 days, and the generation of wrinkles was maintained as it was until 7 days later However, in the subsequent image evaluation, moderate image unevenness occurred in a portion corresponding to the portion.
[0103]
[Comparative Example 1]
In the same manner as in Example 1, a conductive elastic layer was formed on a conductive support.
[0104]
Next, 137 parts by mass of a polyester polyol (trade name “Kyowapol 1000PA (hydroxyl value 112 KOHmg / g)”: manufactured by Kyowa Hakko Co., Ltd.) was dissolved in 463 parts by mass of MIBK (methyl isobutyl ketone), and the solid content was 16.0. % Solution. To 200 parts by mass of this polyester polyol solution, 41.6 parts by mass of the surface-treated conductive tin oxide powder and 0 parts of silicone oil (trade name “SH-28PA” manufactured by Dow Corning Toray Silicone Co., Ltd.) were added. 0.01 parts by mass, 1.14 parts by mass of fine-particle silica (primary particle size: 0.02 μm), elastic particles (trade name “Techpolymer MBX-12” (average particle size: 12 μm): manufactured by Sekisui Plastics Co., Ltd.) ) Was added to 200 parts by mass of glass beads having a diameter of 0.8 mm and placed in a 450 ml mayonnaise bottle, and dispersed using a paint shaker for 6 hours.
[0105]
Further, 29.1 parts by mass of a block type isocyanurate-type trimer (IPDI) of isophorone diisocyanate (trade name “Vestanat B1370”, manufactured by Degussa Huls Co.) was added to 330 parts by mass of this dispersion, and isocyanate of hexamethylene diisocyanate was added. 13.3 parts by mass of a nurate-type trimer (HDI) (trade name “Duranate TPA-B80E”: manufactured by Asahi Kasei Kogyo Co., Ltd.) was mixed, stirred for 1 hour by a ball mill, and finally, the solution was passed through a 200 mesh net. After filtration, the solid content was adjusted to 39.6% by mass to obtain a coating material for a surface layer.
[0106]
The charging member of Comparative Example 1 was obtained by dipping and drying the same coating material under the same conditions as in Example 1. At this time, the thickness of the surface layer was 25 μm, and the electric resistance was 2.3 × 10 ¹⁰ Ω. The electric resistance of this charging member is 2.8 × 10 ⁶ Ω.
[0107]
Further, as a result of viscoelasticity measurement, Tg1 = 90.0 ° C., Tg2 = 108.3 ° C., ΔTg = 18.3 ° C., and crosslink density ρ = 1.2 × 10 ⁴ mol / m ³ Met.
[0108]
When the charging member of Comparative Example 1 was left in an H / H environment for one week and then immediately left in an L / L environment, a slight wrinkle was confirmed at the end three days later, and after four days, the entire charging member was wrinkled. Occurred, and in the subsequent image evaluation, large image unevenness occurred at a portion corresponding to that portion.
[0109]
[Comparative Example 2]
In the same manner as in Example 1, a conductive elastic layer was formed on a conductive support.
[0110]
Next, 76.0 parts by mass of the surface-treated conductive tin oxide powder were added to 200 parts by mass of an aqueous polyurethane (trade name “Superflex 150”: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and silicone oil (product) Name “SH-28PA”: 0.01 parts by mass of Dow Corning Toray Silicone Co., Ltd., 3.00 parts by mass of fine particle silica (primary particle diameter 0.02 μm), elastic particles (trade name “Techpolymer”) MBX-12 "(average particle diameter: 12 µm): 44.00 parts by mass of Sekisui Chemical Co., Ltd. and 200 parts by mass of glass beads having a diameter of 0.8 mm are added, and the mixture is placed in a 450 ml mayonnaise bottle and placed in a paint shaker. And dispersed for 6 hours.
[0111]
Using the above-mentioned paint, dipping was applied under the same conditions as in Example 1 and dried, whereby a charging member of Comparative Example 2 was obtained. At this time, the thickness of the surface layer was 30 μm, and the electric resistance was 3.1 × 10 3 ¹⁰ Ω. The electrical resistance of this charging member was 4.5 × 10 ⁶ Ω.
[0112]
Further, as a result of viscoelasticity measurement, Tg1 = 37.9 ° C., Tg2 = 40.4 ° C., ΔTg = 2.5 ° C., and the crosslink density ρ = 3.4 × 10 ² mol / m ³ Met.
[0113]
When the charging member of Comparative Example 2 was left in an H / H environment for one week and then immediately left in an L / L environment, wrinkles occurred on the entire charging member after three days, and the wrinkles appeared in that portion even in the subsequent image evaluation. Significant image unevenness occurred at the corresponding location.
[0114]
[Comparative Example 3]
In the same manner as in Example 1, a conductive elastic layer was formed on a conductive support.
[0115]
Next, 96 parts by mass of a polyester polyol (trade name “FLEXOREZ 188 (hydroxyl value 230 KOH mg / g)”: manufactured by Kusumoto Kasei Co., Ltd.) was dissolved in 504 parts by mass of MIBK (methyl isobutyl ketone), and the solid content was 16.0 parts by mass. % Solution. To 200 parts by mass of this polyester polyol solution, 41.6 parts by mass of the surface-treated conductive tin oxide powder and 0 parts of silicone oil (trade name “SH-28PA” manufactured by Dow Corning Toray Silicone Co., Ltd.) were added. 0.01 parts by mass, 0.96 parts by mass of fine-particle silica (primary particle size 0.02 μm), elastic particles (trade name “Techpolymer MBX-12” (average particle size 12 μm): manufactured by Sekisui Plastics Co., Ltd.) ) And 200 parts by mass of glass beads having a diameter of 0.8 mm were added to a 450 ml mayonnaise bottle, and dispersed using a paint shaker for 24 hours.
[0116]
Further, 27.3 parts by mass of isocyanurate-type trimer of hexamethylene diisocyanate (HDI) (trade name “Duranate TPA-B80E”: manufactured by Asahi Kasei Kogyo Co., Ltd.) was mixed with 330 parts by mass of the dispersion, and the mixture was mixed with a ball mill. The mixture was stirred for 1 hour, and finally, the solution was filtered through a 200-mesh net to reduce the solid content to 39% by mass to obtain a coating for a surface layer.
[0117]
Using the above-mentioned paint, dipping was applied under the same conditions as in Example 1 and dried, whereby a charging member of Comparative Example 2 was obtained. At this time, the thickness of the surface layer was 20 μm, and the electric resistance was 2.9 × 10 ¹⁰ Ω. The electrical resistance of this charging member was 3.7 × 10 ⁶ Ω.
[0118]
Further, as a result of the viscoelasticity measurement, Tg1 = 106.4 ° C., Tg2 = 112.3 ° C., ΔTg = 5.9 ° C., and the crosslink density ρ = 2.1 × 10 ³ mol / m ³ Met.
[0119]
When the charging member of Comparative Example 3 was left under the H / H environment for one week and immediately left in the L / L environment, wrinkles were generated on the entire charging member after three days, and the wrinkle appeared in that portion in the subsequent image evaluation. Significant image unevenness occurred at corresponding locations.
[0120]
The above evaluation is shown in Table 1.
[0121]
[Table 1]

[0122]
The embodiments of the present invention have been described above. Preferred embodiments of the present invention are listed below.
[0123]
[Embodiment 1]
In a charging member having a conductive elastic layer on a conductive support and having a conductive coating layer as a surface layer on the conductive elastic layer, a glass transition temperature of the conductive coating layer at a relative humidity of 80% is obtained. (Tg1) is 40 ° C. <Tg1 <100 ° C., and the difference ΔTg (= Tg2-Tg1) between the glass transition temperature (Tg2) and the Tg1 of the conductive coating layer at 55% relative humidity is 3 ° C. <ΔTg < A charging member having a temperature of 15 ° C.
[0124]
[Embodiment 2]
The charging member according to embodiment 1, wherein the ΔTg is 7 ° C <ΔTg <15 ° C.
[0125]
[Embodiment 3]
The crosslink density ρ of the conductive coating layer is ρ <1 × 10 ⁴ mol / m ³ 3. The charging member according to embodiment 1 or 2, wherein
[0126]
[Embodiment 4]
The charging member according to any one of Embodiments 1 to 3, wherein the conductive coating layer has a thickness of 10 to 50 µm.
[0127]
[Embodiment 5]
The charging member according to any one of embodiments 1 to 4, wherein the conductive coating layer contains insulating particles having an average particle diameter of 5 to 30 µm with respect to the total weight of the coating layer, in an amount of 5 to 30% by mass.
[0128]
[Embodiment 6]
The charging member according to embodiment 5, wherein the insulating particles are a cross-linkable acrylic resin or an acrylic / styrene copolymer resin.
[0129]
[Embodiment 7]
The charging member according to any one of embodiments 1 to 6, wherein the hardness of the conductive elastic layer is 70 degrees or more in Asker C.
[0130]
[Embodiment 8]
An electrophotographic photoreceptor, the charging member according to any one of embodiments 1 to 7, which is arranged in contact with the electrophotographic photoreceptor and charges the electrophotographic photoreceptor by applying a voltage; A process cartridge detachable from a photographic apparatus main body.
[0131]
[Embodiment 9]
The process cartridge according to claim 8, wherein the voltage applied to the charging member is only a DC voltage.
[0132]
[Embodiment 10]
The electrophotographic photoreceptor, the charging member, the developing unit and the transfer unit according to any one of embodiments 1 to 7, which are arranged in contact with the electrophotographic photoreceptor and apply a voltage to charge the electrophotographic photoreceptor. An electrophotographic apparatus, comprising:
[0133]
[Embodiment 11]
The electrophotographic apparatus according to embodiment 10, wherein the voltage applied to the charging member is only a DC voltage.
[0134]
【The invention's effect】
As described above, according to the present invention, a change in surface properties due to a sudden environmental change, that is, by suppressing surface wrinkles and controlling the surface properties, excellent charging uniformity even when only a DC voltage is applied. Thus, a charging member that does not cause image defects, a process cartridge using the charging member, and an electrophotographic apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a cross section of a charging roller as a charging member of the present invention.
FIG. 2 is an enlarged view of a cross section of the charging member of the present invention.
FIG. 3 is a schematic view showing an example of the charging device of the present invention.
FIG. 4 is a schematic view showing a charging roller current value measuring device which is a charging member of the present invention.
[Explanation of symbols]
11 conductive support
12 conductive elastic layer
13 Surface layer
14 Elastic particles
21 Image carrier (electrophotographic photoreceptor)
22 Charging member (charging roller)
23 Exposure means
24 Developing means
24a toner carrier
24b Stirring part
24c Toner regulating member
25 transfer means
26 Cleaning means
27 Process cartridge
31 Cylindrical electrode (metal roller)
32 fixed resistor
33 Recorder (Recorder)
L laser light
S1, S2, S3 bias application power supply
P transfer material

Claims (3)

In a charging member having a conductive elastic layer on a conductive support and having a conductive coating layer as a surface layer on the conductive elastic layer, a glass transition temperature of the conductive coating layer at a relative humidity of 80% is obtained. (Tg1) is 40 ° C. <Tg1 <100 ° C., and the difference ΔTg (= Tg2-Tg1) between the glass transition temperature (Tg2) and the Tg1 of the conductive coating layer at 55% relative humidity is 3 ° C. <ΔTg < A charging member having a temperature of 15 ° C. The electrophotographic photosensitive member, the charging member according to claim 1, which is arranged in contact with the electrophotographic photosensitive member and charges the electrophotographic photosensitive member when a voltage is applied thereto, and is attached to and detached from an electrophotographic apparatus main body. A process cartridge characterized by being flexible. An electrophotographic photosensitive member, comprising: the charging member according to claim 1, a developing unit, and a transfer unit, which are arranged in contact with the electrophotographic photosensitive member and charge the electrophotographic photosensitive member by applying a voltage. Electrophotographic apparatus.

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